Question

The yellow coloured flame is of

• A. $Na$
• B. $K$
• C. $Ca$
• D. $Ba.$

Answer 1

The correct option is A $Na$

Sodium atom in an unexcited state has the structure $1s^{2}2s^{2}2p^{6}3s^1$ but within the flame, there will be all sorts of excited states of the elements. Sodium's bright yellow flame colour results from promoted electrons falling back from the $3p^1$ level to their normal $3s^1$ level. The yellow coloured flame is of Sodium.

Option A is correct.